Moby Thesaurus II by Grady Ward, 1.0:

44 Moby Thesaurus words for "overmatched":
   all up with, beat, beaten, bested, confounded, defeated,
   discomfited, done for, done in, down, fallen, fixed, floored,
   hors de combat, lambasted, lathered, licked, on the skids, outdone,
   overborne, overcome, overmastered, overpowered, overridden,
   overthrown, overturned, overwhelmed, panicked, put to rout, routed,
   ruined, scattered, settled, silenced, skinned, skinned alive,
   stampeded, trimmed, trounced, undone, upset, whelmed, whipped,
   worsted